Remove hack to disable double-tap to zoom gesture for PDF viewer

This effectively reverts
https://chromium-review.googlesource.com/c/chromium/src/+/614084
which added this hack.

This is no longer necessary as wheel listeners can now prevent the
double-tap to zoom gesture (see issue 802369) and the PDF viewer has
the necessary behaviour already (see testPreventNativeZoomFromWheel in
gesture_detector_test.js).

Bug: 676668, 802369
Change-Id: I4cb840d9f383c0f8aa4a47851d749de41004816b
Reviewed-on: https://chromium-review.googlesource.com/c/1281172Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599975}

chrome/browser/pdf/pdf_extension_test.cc

@@ -1774,24 +1774,6 @@ void EnsureCustomPinchZoomInvoked(WebContents* guest_contents,
 
 #if defined(OS_MACOSX)
 
-// Test that "smart zoom" (double-tap with two fingers on Mac trackpad)
-// is disabled for the PDF viewer. This prevents the viewer's controls from
-// being scaled off screen (see crbug.com/676668).
-IN_PROC_BROWSER_TEST_F(PDFExtensionTest, SmartZoomDisabled) {
-  GURL test_pdf_url(embedded_test_server()->GetURL("/pdf/test.pdf"));
-  ASSERT_TRUE(LoadPdf(test_pdf_url));
-
-  blink::WebGestureEvent smart_zoom_event(
-      blink::WebInputEvent::kGestureDoubleTap,
-      blink::WebInputEvent::kNoModifiers,
-      blink::WebInputEvent::GetStaticTimeStampForTests(),
-      blink::kWebGestureDeviceTouchpad);
-  smart_zoom_event.data.tap.tap_count = 1;
-
-  EXPECT_TRUE(browser()->PreHandleGestureEvent(GetActiveWebContents(),
-                                               smart_zoom_event));
-}
-
 // Ensure that Mac trackpad pinch events are handled by the PDF viewer.
 IN_PROC_BROWSER_TEST_F(PDFExtensionTest, TrackpadPinchInvokesCustomZoom) {
   GURL test_pdf_url(embedded_test_server()->GetURL("/pdf/test.pdf"));

chrome/browser/ui/browser.cc

@@ -218,11 +218,6 @@
 #include "ui/gfx/geometry/point.h"
 #include "ui/shell_dialogs/selected_file_info.h"
 
-#if defined(OS_MACOSX)
-#include "content/public/browser/browser_plugin_guest_manager.h"
-#include "extensions/browser/process_manager.h"
-#endif
-
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
@@ -1321,29 +1316,6 @@ bool Browser::TabsNeedBeforeUnloadFired() {
 
 bool Browser::PreHandleGestureEvent(content::WebContents* source,
                                     const blink::WebGestureEvent& event) {
-#if defined(OS_MACOSX)
-  // Disable "smart zoom" (double-tap with two fingers on Mac trackpad)
-  // for the PDF viewer, otherwise the viewer's controls will be scaled off
-  // screen.
-  // TODO(mcnee): Investigate having the PDF viewer handle the gesture
-  // once it is a service. crbug.com/757541
-  if (event.GetType() == blink::WebInputEvent::kGestureDoubleTap) {
-    content::BrowserPluginGuestManager* guest_manager =
-        source->GetBrowserContext()->GetGuestManager();
-    if (guest_manager) {
-      const content::WebContents* guest_contents =
-          guest_manager->GetFullPageGuest(source);
-      if (guest_contents) {
-        const extensions::Extension* extension =
-            extensions::ProcessManager::Get(guest_contents->GetBrowserContext())
-                ->GetExtensionForWebContents(guest_contents);
-        if (extension && extension->id() == extension_misc::kPdfExtensionId)
-          return true;
-      }
-    }
-  }
-#endif  // defined(OS_MACOSX)
-
   // Disable pinch zooming in undocked dev tools window due to poor UX.
   if (app_name() == DevToolsWindow::kDevToolsApp)
     return blink::WebInputEvent::IsPinchGestureEventType(event.GetType());